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A protein is a sequence of many amino acids. All proteins are made of amino acids. Humans have 20 distinguished amino acids that can arrange in thousands of different combinations and this means that they...

P wave: atrial depolarisation and subsequent contraction. QRS complex: Ventricular depolarisation and subsequent contraction. Q wave is negative due to left to right depolarisation of ventricular septum. ...

Firstly, the alveoli walls consist of a one-cell thick layer of squamous epithelium. This means there is a thin barrier to diffusion, and a small distance for oxygen molecules to diffuse across to get to ...

Leguminous plants have nodules on their roots that contain, symbiotic bacteria. These bacteria are capable of turning gaseous nitrogen ultimately to nitrate, which the plant can then use in order to synth...

A reflex action is the body's rapid, involuntary response to external stimuli, often used in order to protect it from immediate harm. First, a receptor detects a stimulus, such as a heat source which coul...